1. Field of the Invention
This invention relates to fiber optic connectors, and in particular to an arrangement for integrating a rectangular fiber optic connector into a cylindrical connector.
2. Description of Related Art
The fiber optic connector commonly known as the Mechanical Transfer (MT) connector, but more accurately described as an MT ferrule, is essentially a housing that encapsulates the ends of a plurality of fibers and thus aids in aligning the fibers so that the ends of the fibers can be mechanically joined together to establish a connection between two groups of fibers in a manner analogous to the connection made by an electrical connector. Use of MT connectors facilitates coupling of the fibers because it is only necessary to align the MT connectors in order to align the fibers, rather than having to align individual fibers.
Conventionally, MT connectors or ferrules are pre-formed around the ends of fibers extending from a fiber optic ribbon cable, and thus are most conveniently formed into a parallelepiped shape, referred to herein as a "rectangular" shape. In order to utilize the MT connectors, they are integrated into a rectangular housing that provides coupling and alignment functions.
Even though rectangular fiber optic coupler arrangements are becoming quite common, and follow naturally from the shape of the MT ferrules, there are many situations where cylindrical couplers may be preferred for ease-of-handling and mounting. In military applications especially, cylindrical electrical connector standards have been the norm for many years and in upgrading from electrical to fiber optic cabling it would be highly advantageous if the standards did not have to be re-written in all situations to cover rectangular configurations, enabling existing hardware and environmental sealing arrangements to continue to be utilized.
As a result, it has previously been proposed to integrate rectangular fiber optic connectors into cylindrical connector housings. However, such integration has previously required specially designed connector housings arranged to collectively accommodate multiple rectangular fiber optic connectors, examples of which are described in U.S. Pat. Nos. 4,142,776 and 5,689,598. Other references showing cylindrical fiber optic connector configurations include U.S. Pat. Nos. 5,715,342, 5,283,848, 5,000,536, 4,174,882, and 4,140,367. In contrast, the present invention encloses the rectangular fiber optic connectors or ferrules in individual shells, which can then be inserted in a generally standard cylindrical connector housing or shell.
In addition to references showing rectangular fiber optic connectors integrated into cylindrical connector shells, the related art for the present invention includes a reference, U.S. Pat. No. 5,619,604, showing enclosure of individual rectangular fiber optic connectors in a rectangular connector shell. The present invention also uses the principle of enclosing individual fiber optic connectors in individual connector shells, but does so in a way that enables their use in cylindrical connectors, avoiding the complexities and lack of uniform standards suffered by prior cylindrical fiber optic connector configurations.
Also of interest as background for the present invention are refer U.S. Pat. Nos. 5,553,157 and 5,104,242 which show shutter arrangements for fiber optic connectors. One of the features of the present invention is a shutter mechanism that, unlike those of U.S. Pat. Nos. 5,553,157 and 5,104,242, is a torsion-spring based rotary shutter mechanism adapted for use in a cylindrical multiple contact connector shell or housing.
While the invention generally covers an arrangement for utilizing rectangular MT connectors in cylindrical connectors, and is not to be limited to a particular cylindrical connector configuration, an example of a cylindrical connector configuration currently used for electrical connectors, but which could be adapted using the principles of the invention to couple fiber optic cables, is the cylindrical connector known as the MIL-C-38999 Series III connector (the identification number of the connector referring to a U.S. Department of Defense connector specification), which is similar to the connectors illustrated in U.S. Pat. Nos. 4,746,310 and 5,211,582, in its use of removable cylindrical contacts (referred to as size 8 contacts) held in place within the connector by an insert assembly having a plurality of bores for individual contacts, the contacts being held in place by engagement between shoulders on the contacts and tines extending inwardly from the bores that flex to permit the contacts to be snapped into place, and that permit the contacts to be removed by a tool arranged to be inserted into the bores in order to disengage the tines from the shoulders.
In designing connectors to meet military specifications, robustness, standardization, and ease-of-use, installation, and servicing under difficult conditions are all of critical importance, and it is the objective of the invention to meet these goals by adapting the conventional MT connector or ferrule for use in military style cylindrical multiple contact connectors. It should nevertheless be appreciated that the goals of the military are also relevant to civilian applications such as avionics, and that the invention is not limited to "Mil Spec" connectors, or to any particular cylindrical connector configuration.